Slotted compressor blades



Aug. 21, 1956 E. A. STALKER SLOTTED COMPRESSOR BLADES Filed Jan. 12, 1953 I .Illlll! Edvvvl /ll'Z i l ll I ll l 40 rr i FIG 7 United States Patent Office Patented Aug. 21, 1956 SLOTTED COMPRESSGR BLADES Edward A. Stalker, Bay City, Mich., assignor to The Stalker Development Company, Bay City, Mich., a corporation of Michigan Application January 12, 1953, Serial No. 330,606 Claims. (Cl. 230-134) This invention relates to bladed fluid machines for interchanging energy with a iiuid and particularly to blades having openings in their surface through which to control the boundary layer thereon.

An object of the invention is to provide a slotted blade which has great strength and rigidity.

Another object is to provide a slotted sheet metal blade which is able to resist fatigue failure from vibration.

Other objects will appear from the description, drawings and claims.

The above objects are accomplished by the means illustrated in the accompanying drawings in which- Fig. 1 is an elevation of a slotted axial flow compressor blade;

Fig. 2 is a section on line 2 2 in Fig. 1;

Fig. 3 is a section on line 3--3 in Fig. l;

Fig. 4 is an elevation of another blade having a suction slot;

Fig. 5 is a section on line 5-5 in Fig. 4;

Fig. 6 is a section on line 6-6 in Fig. 4; and

Fig. 7 is a fragmentary axial section through a compressor.

Referring now to the drawings Fig. l shows a View of a blade indicated generally as 10 comprised of the skin or envelope 12, the skin or envelope 14, and the stem 16.

The envelope encloses the stem and is fused to it on the lower surface 20, the upper surfaces 22 and 23, and to the splines 24. The envelope defines the discharge slot 26 facing rearward to discharge liuid rearward along the blade surface.

At a chordwise side of the stem there is the spanwise channel 30 extending along the span of the blade and through the base 32.

If a fluid pressure is applied to the inlet at the base different from that outside the slot in the region thereof fluid will enter the channel through the base and will ow spanwise to the various flutes 34 defined between the spanwise spaced splines 24.

The stem 16 bridges the slot 26 while still directing a flow therethrough. The stem confers torsional rigidity on the blade even though the envelope has the slot 26.

The stem 16 and the base 32 are rigidly connected.

The skins 12 and 14 are preferably soldered to the faying surfaces of the stem.

In Figs. 4-6 the blade 40 has an induction slot 42 defined by the envelope parts 44 and 46. The parts fore and aft of the slots are tied together by the stem 48.

Fig. 7 shows the blades 10 and 40 installed in an axial ow compressor. The increased static pressure of the fluid at blades 40 induces a iiow into each blade and through the duct 80 to each blade 10 where the inducted Huid is emitted from slot 26.

The stem has a plurality of chordwise splines 50 which ties the two sections 52 and 54 of the stem together. The splines define a plurality of chordwise flutes 56 which communicate at opposite ends with the spanwise channels 60 and 62. Thus suction applied to the root or hub ends of the channels 60 and 62 will induce a ow of uid into the slot 42, through the utes 56 into the channels 60 and 62.

The splines at about their chordwise center extend upward between the two sections of the stem.

At the slots the skin has the inward turned tianges 70 and 72 respectively fused to opposite sections of the stem.

When a slot extends spanwise in a blade wall the torsional strength and rigidity is greatly reduced. Thus the 'blade tends to fail Iby vibration in the skin unless the opposite sides of the slot are tied together by a relatively rugged structure. In both the blades, one having a discharge slot and the other a suction slot, the stem of solid construction, that is integral, bridges the slot providing a strong and rigid structure capable of passing a boundary layer control flow.

The structure described facilitates the construction of a blade having a slot or opening means in its outer wall or surface. For instance the stems 16 and 48 constituting a core means are readily provided with the flutes or passages 34 and 56 by tools working inward from the surface of the stem. These are much easier to construct than passages completely enclosed by walls. After the stern or core is constructed the skin or envelope is wrapped about the stem and fused along the faying surfaces.

While I have illustrated specific forms of the invention, it is to be understood that variations may -be made therein and that I intend to claim my invention broadly as indicated by the appended claims.

I claim:

l. In combination in a slotted compressor blade of the axial liow type, a blade skin of sheet metal defining a blade contour, said skin having a slot in the upper side thereof extending spanwise along a major portion of the blade span, a stem enclosed in said skin and spaced therefrom at one chordwise side defining a spanwise extended channel, said stem having front and rear portions defining a slot therebetween extending through between upper and lower sides thereof, said skin slot registering with said stem slot, said stern slot being in communication with said channel for flow of a uid from one to the other through said skin slot, said stern portions being bonded by fused metal to said skin adjacent to said skin slot with the sides thereof fairing with the sides of said stem slot for establishing streamline ow in said slots, said stem being also bonded by fused metal to said skin on the lower side of said stem, said skin extending continuously from the leading to the trailing edge of said blade to develop fatigue strength therein, said stem having integral spanwise spaced splines extending from one said portion to the other across said stem slot, both said portions extending spanwise continuously along substantially the whole spanwise extent of said skin slot and at least one portion extending continuously from the skin at said upper side to the skin at said lower side and being xed to said skin at both said sides, providing adequate strength of said blade against vibratory fatigue` failure at localities adjacent to said slot.

2. In combination in a slotted compressor blade of the axial ow type, a blade skin of sheet metal defining a blade contour, said skin having a slot in the upper side thereof extending spanwise along a major portion of the blade span, a stem enclosed in said skin and spaced therefrom at one chordwise side defining a spanwise extended channel, said stem having front and rear portions de lining a slot therebetween extending through between upper and lower sides thereof, said skin slot registering with said stem slot, said stem portions having spanwise spaced splines formed in the under sides thereof defining open sided chordwise directed utes between said splines in communication with said channel and said skin slots, said splines extending upward along said stem slot and from one said portion tothe otherA said slot integral with said portions, said. skin. being fixed tosaid splines byy fused metal and extending continuously from the leading edge to the trailing edge of said blade, both said portions having substantialf thickness perpendicular-to` the chord direc-- tion of said blade and:` both extending spanwise contin-` uously along substantially the whole spanwiseextent: of said skin. slot and beingf fixed; tot said: skin on. opposite sides of said slot byA fusedmetad, prouidinge adequate. strength of said blade against vibratory fiailure at localities. adiaecnt to said slot..

3|.. In combination in,` a slotted. eompressor blade of the axial fiow type, a blade skin'L off sheet. metal defining a blade contour, said skin havingl a slot in the upper side thereof extending. spanwise: along a major portion. of. the blade span, a. stemt enclosedin said skin and. spaced therefronr atY one chordwise side:defining` at spanwise extended channel,. said stern having; front; and*` rear portions defining aslotv therebetween extending through; between upper and. lower sides thereof, said skin slot registering with said stern slot,1 said stemthauing spa-nwise spaced. spline formed in; the underside thereofdefining-open. sides liutes in cornniunicat'ion with said skinl slot and with said channel at localities distributed alongv saidblade,l said, splines extending in.- the general. perpendicular. direction to the blade chord along saidstent slot and from one said portion to the other acrossj said slot. integral with said` portions, said skinr being fixed. to saidl splines by fused metal. and extending continuously, from. the leading edge to the trailing edge of said blade, both, said portions having substantial thickness perpendicular. tothe chord direction of. said blade and both` extending spanwise continuously along substantially the Whole. spanwise extent of said skin slot and being fixed to said skin on opposite sides. of'` said slot by fused rnetal,. providing. adequate strength of said blade against vibratoryffailureat localities adjacent. to said slot.

4. in combination, in a slotted compressor blade ofthe axial iiow type, a blade skin of sheet metal defining, a blade contour,l said skin havingv a slot in the upper side thereof extending spanwise along a rnajfor portion of the blade span, a sternenclosed in said skin and spaced' therefrom at one chordwse side definingA a spanwise extended channel', a blade base abutting said skin and being fixedA to said` stem and having an opening. into said channel', said stern having frontY and rear portions deining a slotv therebetween extending throughbetween upper and lower sides thereof, said skin slot, registering With said Stemslot, said stem. having spanwise spaced splines formed in the underside thereof definingv openy sided` flutes in cornmunication with. said skin slot and with said channel at localities distributed! along. said blade, said splines extending in the general perpendicular direction to the blade chord along saidl stem slot a-nd frornone' said' portion to the other across said slot integral with said portions, said skin being fixed to said splines by fused metal and extending continuously from the leading edge to the trailing edge of said blade, both said portions having substantial thickness perpendicular to the chord direction of said blade and both extending spanwise continuously along substantially the whole spanwise extent of said skin slot and` being, fixed. to said skin on, opposite sides of said slot by fused. metal, providing adequate strength. of said blade against vibratory failure at localities adjacent to said` slot.

5. In combination in a slotted compressor blade of the axial flow type, a blade skin of sheet metal defining a blade contour, said skin having at slot: in: the upper side thereof extending spanwise along a major portion of the lade span, a stern enclosed in said skin and spaced therefrom at one chordwise side defining a spanwise extended channel, said stern having front andi rear portions defining a slot therebetween extending through bet-Ween upper and. lower sides thereof, said skin slot` registering with said stem sl'ot, said sternx portions having spanvvise spaced spline formed in the under sides thereof defining open sided chordwise directed flutes. betweensaid splines in communication with. saidl channel. andi said sk-i'n slots, said splines extending upward along saidv stern slot' and from one said portion to the other across saidy slotintegral with said portions, said skin being fixed tot sairli splines by fused metal and extending continuously from the leading edge. to the trailing. edge of said blade, both'. said portions hat/ing substantial. thickness perpendicular to the chord direction of said blade and both extending spanwise continuously along substantially the wholle spanwise extent of said. skin slot and being fixed tot said skin on-1 opposite sides of said slot by fusedy metaL. said stem fixing the upper part of said skin between said slot and the trailing edge of said'v blade rigidly to the part of the said skin forward of said slot,.providng adequatezstrength ofv said blade against vibratory failure at localities: adjacent to said slot.

ReferencesY Cited in the file of this patent:

UNITEDI STATES PATENTS.

2,169,325 Novak Aug. l5, T939.

2,344,835 Stalker Mar. 2'l, 1944 2,476,062 Stalker July' l2, 1949 2,638,990 Pitcairn May l9, l`3

FOREIGN PATENTS 768,647 France May 22, 129344 

